Sunanda Pushkar Tharoor, 52, was found dead on Friday in a luxury hotel in Delhi. She had used Twitter to allege that her husband, Shashi Tharoor, had had an affair with a Pakistani journalist.

One of the doctors who carried out the autopsy said that "more tests" are needed to determine the final cause of Mrs Tharoor's death, and the results will not be known for two to three days.

Ms Tharoor, the wife of Shashi Tharoor, minister for human resource development, had hacked her husband's Twitter account and posted private messages between him and the woman she alleged was his mistress.

She had continued to post messages criticising the woman, Mehr Tarar, a Pakistani journalist, for "stalking" her husband. The messages continued into the early hours of Friday morning.

A spokesman for the minister said Mr Tharoor had found her dead on the bed of their room at the Leela Hotel when he returned from a Congress Party rally in Delhi on Friday evening.

Mr Tharoor’s private secretary Abhinav Kumar said in a statement outside the hotel that he was confirming the death “with great sadness”.

“She was found in a hotel room in her bed at 8.30pm. The police, a forensic team and the magistrate are on the spot. The cause of death is unknown," he said.

"After completing the formalities, the body will be taken for a post-mortem and then [we’ll] get an idea of the cause of death. She was fully clothed. There was no sign of foul play or poisoning. We don’t know whether it was from natural causes.”

News of Mrs Tharoor’s death caused shock throughout India’s political establishment and Mr Tharoor's fellow ministers sent messages of condolence.

Ms Tarar, the woman Mrs Tharoor had accused of having an affair with her husband, also reacted with shock at the news.

She wrote on Twitter: “What the hell. Sunanda. Oh my God.”

And then added: “I just woke up and read this. I’m absolutely shocked. This is too awful for words. So tragic. I don’t know what to say. Rest in Peace, Sunanda.”

The controversy first erupted on the social media site on Wednesday when Mrs Tharoor leaked a series of private messages between her husband and Ms Tarar on his Twitter account.

In one of the first messages, which appeared to be from Ms Tarar to Mr Tharoor, the journalist allegedly said: “I love you, Shashi Tharoor. And I go while in love with you, irrevocably, irreversibly, hamesha [always]. Bleeding, but always your Mehr.”

The minister later issued a statement claiming his Twitter account had been hacked. But his wife said she had posted the messages on his account to expose how Ms Tarar had "stalked" her husband.

In newspaper interviews she later said they had been having a "rip-roaring" affair and claimed the journalist was a Pakistani spy. She also said she intended to divorce him.

The minister’s wife seemed tired in later telephone interviews on live television, but the couple then appeared to settle their differences and issued a statement saying they remained happily married.

“Sunanda has been ill and admitted to hospital this week and is seeking to rest,” the couple said, and they would not comment further.

But in the early hours of Friday, Mrs Tharoor posted another series of tweets, after Ms Tarar appeared to deny sending private messages via her Blackberry Messenger (BBM) to her husband, accusing her of telling lies.

“@mehrtarar has lied outright. I have all her emails and BBMs to my husband. I don’t lie,” she wrote at around 1.30am on Friday.

It wasn’t clear whether she was in hospital, as has been reported, at the time she posted the tweet, or in the hotel. An hour later she replied to a follower who had asked about her health that “sadly I am too sick at the moment.” She is believed to have been suffering from lupus and a strain of tuberculosis in her stomach.

Friends told local newspapers there had been problems in the couple’s relationship and that Mrs Tharoor had been spending a lot of time in Dubai in the last year.

Earlier on Friday, Mr Tharoor left his wife in their room at the Leela Hotel, where the couple were staying during renovations to their home, to attend a Congress rally for Rahul Gandhi. According to friends, Mrs Tharoor stopped answering phone calls after noon.

Police said that Mr Tharoor returned after 8pm but found the door locked. When the lock was forced, he found his wife dead on the bed.

Mr Tharoor’s son Ishaan, an editor at Time magazine in New York, issued a request that “everyone please respect our family's privacy at this moment.”